I would export the surfaces as an LandXML, under surface description Points and breaklines. Then re-import the XML surfaces and categorize them correctly IE. Original and Design with the 3d triangle layers the XML generated. The layers should be the name the surface is represents. You can then use the 2D linework as your boundaries for site improvements if needed.

I would export the surfaces as an LandXML, under surface description Points and breaklines. Then re-import the XML surfaces and categorize them correctly IE. Original and Design with the 3d triangle layers the XML generated. The layers should be the name the surface is represents. You can then use the 2D linework as your boundaries for site improvements if needed.

Thanks Erik - this is a way to do this - I agree that this could be easier - if the imported surface is made up from Points and Lines then you can use Add / Remove Surface Members to a Takeoff Surface (like Original ground) after the Takeoff surface has been created. That means as a minimum your Takeoff surface has to have one Layer Categorized but it doesn't have to contain any data. Once created it is like any other surface model, you can Add / Remove Surface Members to it and even though those objects may be on layers that are not categorized as Original for Takeoff, the objects will be added and can be used to form the surface. However you cannot do this with a TIN Surface and add the TIN to a Takeoff Surface - it needs to have source Lines and Points to do that at this time.

Note Point Clouds are the same - Point Clouds and Point Cloud Regions do not have a Layer Property, however once your Takeoff Surface has been created (even if it is empty), you can select a Point Cloud Region(s) and add it to the Takeoff Surface and it will then be used in every rebuild of the Takeoff surface thereafter. As it is added we use the Support - Options - Point Clouds settings to control how many points of the Point Cloud region will get added - if your setting for Max Points in a Surface is set to 100,000 then we will add 100,000 points to your Original Ground Takeoff surface through adding the Point Cloud. This applies to each Point Cloud Region that you add one at a time. If you pick 3 point Cloud Regions and add them at the same time then we take 100,000 points total vs 300,000 points doing them one at a time.